Ukraine Death Toll Rises as Gunfights Rage in Restive East

Four Ukrainian soldiers were killed on the outskirts of the eastern city of Slovyansk on Monday, prompting the government to reportedly block flights Tuesday to a region of the country where its forces are struggling to quell pro-Russian fighters.

The blocking of flights, the New York Times reports, came amid a mounting death toll from increasingly pitched battles with pro-Russian militias in the east. Ukraine said militants bearing Russian arms ambushed and killed four of its soldiers on Monday. Moscow denies arming or aiding the militants, while warning Ukraine's fledgling government that it may forcefully intervene if the security situation continues to deteriorate.

Ukraine's interior minister, Arsen Avakov, said that as many as 30 pro-Russian militants may have been killed in chaotic battles outside of Slovyansk. He alleged in a Facebook post that Russian separatists were deliberately positioning themselves behind civilians. "The enemy hides behind people and fires from there," Avakov wrote.

Ukrainian forces have surrounded the city as part of an "anti-terror" operation to oust pro-Russian militants from their strongholds. Rebels have seized control of government buildings in as many as a dozen cities in the east, BBC reports.

The fissure between the eastern region and the government in Kiev widened Tuesday, as Ukrainian authorities appeared to halt all international flights to the restive cities. As many as 20 flights from Kharkiv and Donetsk were cancelled, the Times reports. Meanwhile, the government said it had surrounded Kiev with checkpoints, in anticipation of a public holiday on Friday which officials feared could descend into violence.